Investigations are being conducted on sound detection mechanisms in teleost fishers. Psychophysical and physiological experiments are beingused to determine methods of sound detection and how the detected signals are processed in the swim bladder and inner ear. In addition, behavioral auditory capabilities will be determined for a number of species and these data will be compared with data obtained in physiological experiments. Physiological experiments include measurement of saccular potentials, tuning curves of neurons in the 8th nerve, and response of the swim bladder to sound stimulation using a microphone 'inside' ofthe swim bladder. Psychophysical experiments include studies of masking, pulse tone detection and pure-tone thresholds.